Method of assembling and positioning a femoral orthopaedic surgical instrument

ABSTRACT

A method for performing an orthopedic surgical procedure on a femur includes attaching a proximal end of an intramedullary adaptor to an intramedullary orthopedic surgical instrument, securing a distal end of an intramedullary adaptor to a base cutting block, inserting the intramedullary orthopedic surgical instrument into a medullary canal using the base cutting block, and positioning the base cutting block on a distal end of the femur.

This application is a continuation of U.S. patent application Ser. No.13/485,497, now U.S. Pat. No. 9,138,238, filed May 31, 2012, whichclaims priority under 35 U.S.C. §119 to U.S. Patent Application No.61/653,359, which was filed on May 30, 2012. Each of those applicationsis incorporated herein by reference.

CROSS-REFERENCE

Cross reference is made to U.S. patent application Ser. No. 13/485,502,now U.S. Pat. No. 9,084,612, entitled “FEMORAL ORTHOPAEDIC SURGICALINSTRUMENTS AND METHOD OF USE OF SAME”; and U.S. patent application Ser.No. 13/485,470, now U.S. Pat. No. 9,050,107, entitled “METHOD OFSURGICALLY PREPARING A PATIENT'S FEMUR”, each of which is assigned tothe same assignee as the present application, each of which is filedconcurrently herewith, and each of which is hereby incorporated byreference.

TECHNICAL FIELD

The present disclosure relates generally to orthopaedic instruments foruse in the performance of an orthopaedic joint replacement procedure,and more particularly to orthopaedic surgical instruments for use in theperformance of a revision knee replacement procedure.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which adiseased and/or damaged natural joint is replaced by a prosthetic joint.For example, in a total knee arthroplasty surgical procedure, apatient's natural knee joint is partially or totally replaced by aprosthetic knee joint or knee prosthesis. A typical knee prosthesisincludes a tibial tray, a femoral component, and a polymer insert orbearing positioned between the tibial tray and the femoral component.The tibial tray generally includes a plate having a stem extendingdistally therefrom, and the femoral component generally includes a pairof spaced apart condylar elements, which include surfaces thatarticulate with corresponding surfaces of the polymer bearing. The stemof the tibial tray is configured to be implanted in asurgically-prepared medullary canal of the patient's tibia, and thefemoral component is configured to be coupled to a surgically-prepareddistal end of a patient's femur

From time-to-time, a revision knee surgery may need to be performed on apatient. In such a revision knee surgery, the previously-implanted kneeprosthesis is surgically removed and a replacement knee prosthesis isimplanted. In some revision knee surgeries, all of the components of thepreviously-implanted knee prosthesis, including, for example, the tibialtray, the femoral component, and the polymer bearing, may be surgicallyremoved. In other revision knee surgeries, only part of thepreviously-implanted knee prosthesis may be removed and replaced.

During a revision knee surgery, the orthopaedic surgeon typically uses avariety of different orthopaedic surgical instruments such as, forexample, cutting blocks, reamers, drill guides, prosthetic trials, andother surgical instruments to prepare the patient's bones to receive theknee prosthesis.

SUMMARY

According to one aspect of the disclosure, an orthopaedic surgicalinstrument assembly is disclosed. The orthopaedic surgical instrumentassembly includes a base cutting block, an intramedullary orthopaedicsurgical instrument, and an adaptor. The base cutting block includes abase plate including a proximal surface, a distal surface positionedopposite the proximal surface, and a slot extending through the proximalsurface and the distal surface. The base cutting block also includes apair of curved arms extending posteriorly from the base plate. Eachcurved arm includes a posterior surface shaped to match a posteriorcondyle surface of a femoral prosthetic component and a cutting guidedefined in the posterior surface. The intramedullary orthopaedicsurgical instrument is configured to be inserted into a medullary canalof a patient's femur. The adaptor is positioned in the slot defined inthe base plate. The adaptor includes a mounting bracket engaged with thebase plate and a fastener coupled to the intramedullary orthopaedicsurgical instrument.

In some embodiments, the base cutting block may include a locking tabpivotally coupled to the base plate. The locking tab may be moveablebetween a first position in which the locking tab is engaged with themounting bracket to secure the adaptor to the base cutting block, and asecond position in which the locking tab is disengaged from the mountingbracket such that the adaptor is removable from the base cutting block.

In some embodiments, the adaptor may further include an adaptor bodycoupled to the mounting bracket. The adaptor body may have alongitudinal axis that forms an oblique angle a distal surface of themounting bracket.

In some embodiments, the locking tab of the base cutting block may be afirst locking tab and the base cutting block may include a secondlocking tab pivotally coupled to the base plate. The mounting bracketmay include a first arm extending outwardly from the adaptor body and asecond arm extending outwardly from the adaptor body opposite the firstarm. The first arm may have a channel defined therein that is sized toreceive the first locking tab, and the second arm may have a channeldefined therein that is sized to receive the second locking tab.

In some embodiments, the adaptor body may include a passageway thatextends along the longitudinal axis, and the fastener may be pivotallycoupled to the adaptor body. The fastener may include a threaded shaftextending outwardly from the adaptor body and a head retained in thepassageway. The head may have a socket shaped to receive a surgical toolto rotate the fastener relative to the adaptor body.

Additionally, in some embodiments, the intramedullary orthopaedicsurgical instrument may include a stem stabilizer having aninternally-threaded first end. The internally-threaded first end may beengaged with the threaded shaft of the fastener. The stem stabilizer mayalso have an internally-threaded second end positioned opposite thefirst end. The intramedullary orthopaedic surgical instrument may be astem trial including an externally-threaded end that is engaged with theinternally-threaded second end of the stem stabilizer.

In some embodiments, the stem stabilizer may include a body having thefirst end and the second end and a pair of fins extending outwardly fromthe body.

In some embodiments, the orthopaedic surgical instrument assembly mayfurther include a guide block configured to be positioned in the slotdefined in the base plate in place of the adaptor. The guide block mayinclude a mounting bracket configured to engage with the base cuttingblock, and a bushing having a cylindrical passageway defined thereinsized to receive an orthopaedic surgical instrument.

In some embodiments, the orthopaedic surgical instrument assembly mayfurther include a plurality of modular cutting blocks configured to beseparately secured to an anterior side of the base plate.

According to another aspect of the disclosure, an orthopaedic surgicalinstrument assembly includes a base cutting block. The base cuttingblock has a base plate including a proximal surface, a distal surfacepositioned opposite the proximal surface, and a slot extending throughthe proximal surface and the distal surface. The base cutting block alsoincludes a locking tab having a body positioned between the proximalsurface and the distal surface of the base plate and an ear. The body ofthe locking tab is pivotally coupled to the base plate and moveablebetween a first position in which the ear of the locking tab ispositioned in the slot and a second position in which the ear is spacedapart from the slot. The base cutting block has a pair of curved armsextending posteriorly from the base plate. Each curved arm includes aposterior surface shaped to match a posterior condyle surface of afemoral prosthetic component and a cutting guide defined in theposterior surface.

In some embodiments, the orthopaedic surgical instrument assembly mayfurther include a first orthopaedic surgical instrument including amounting bracket. When the body of the locking tab is in the firstposition, the ear of the locking tab may be engaged with the mountingbracket to secure the first orthopaedic surgical instrument to the baseplate. When the body is in the second position, the ear of the lockingtab may be disengaged from the mounting bracket such that the firstorthopaedic surgical instrument is removable from the base plate.

Additionally, in some embodiments, the orthopaedic surgical instrumentassembly may further include a second orthopaedic surgical instrumentconfigured to be secured to a proximal end of the first orthopaedicsurgical instrument. The second orthopaedic surgical instrument may bean intramedullary orthopaedic surgical instrument.

In some embodiments, the orthopaedic surgical instrument assembly mayfurther include a plurality of modular cutting blocks configured to beseparately secured to an anterior side of the base plate. In someembodiments, the plurality of modular cutting blocks may include ananterior cutting block having an anterior cutting guide.

Additionally, in some embodiments, at least one of the cutting guidesdefined in the curved arms of the base cutting block may define animaginary plane. In some embodiments, the plurality of modular cuttingblocks may include a distal cutting block configured to be secured tothe base plate in place of the anterior cutting block. The distalcutting block may have a plurality of distal cutting guides. When thedistal cutting block is secured to the base plate, each distal cuttingguide may extend transverse to the imaginary plane and parallel to theother distal cutting guides.

In some embodiments, the plurality of modular cutting blocks may includea notch cutting block configured to be secured to the base plate inplace of the anterior cutting block. The notch cutting block may includea first cutting guide having a first cutting guide surface that extendstransverse to the imaginary plane, and a second cutting guide surfaceconnected to the first cutting guide surface. The second cutting guidesurface may extend transverse to the imaginary plane and orthogonal tothe first cutting guide surface.

In some embodiments, the notch cutting block may further include asecond cutting guide that extends obliquely relative to the imaginaryplane.

In some embodiments, the orthopaedic surgical instrument assembly mayfurther include a spacer block configured to be secured to the proximalsurface of the base cutting block. In some embodiments, the orthopaedicsurgical instrument assembly may further include a shim sized to bereceived in one of the cutting guides defined in the curved arms of thebase cutting block.

According to another aspect, an orthopaedic surgical instrument assemblyincludes a base block, an intramedullary orthopaedic surgical instrumentconfigured to be inserted into a medullary canal of a patient's femur,an adaptor, and a plurality of modular cutting blocks. The base blockincludes a base plate including a proximal surface, a distal surfacepositioned opposite the proximal surface, and a slot extending throughthe proximal surface and the distal surface. The intramedullaryorthopaedic surgical instrument is configured to be inserted into amedullary canal of a patient's femur. The adaptor is positioned in theslot defined in the base plate. The adaptor includes a mounting bracketengaged with the base plate, and a fastener coupled to theintramedullary orthopaedic surgical instrument. The plurality of modularcutting blocks is configured to be separately secured to an anteriorside of the base plate.

According to another aspect, a method of surgically preparing a distalend of a femur for implantation of a femoral prosthetic component isdisclosed. The method includes positioning a base cutting block and anintramedullary adaptor on the distal end of the femur such that a firstend of the intramedullary adaptor is received in the medullary canal ofthe femur and the intramedullary adaptor is secured to the base cuttingblock, attaching a first modular cutting block to an anterior side ofthe base cutting block, and resecting a first portion of the distal endof the femur using a cutting guide defined in the first modular cuttingblock. The method also includes resecting a first portion of the distalend of the femur using a base cutting guide defined in the base cuttingblock, attaching a second modular cutting block to the anterior side ofthe base cutting block in place of the first modular cutting block, andresecting a third portion of the distal end of the femur using a cuttingguide defined in the second modular cutting block. The cutting guide ofthe second modular cutting block extends transverse to the imaginaryplane defined by the base cutting guide.

In some embodiments, the method may further include determining anamount of bone to be resected when the second modular cutting block isattached to the base cutting block, and selecting from a plurality ofcutting guides defined in a body plate of the second modular cuttingblock the cutting guide corresponding to the amount of bone to beresected. In some embodiments, the method of claim may further includepivoting a pin guide of the second modular cutting block relative to thebody plate while maintaining the body plate in position on an anteriorsurface of the femur, and inserting a pin through a passageway definedin the pin guide into the anterior surface of the femur.

In some embodiments, the method may further include attaching a thirdmodular cutting block to the anterior side of the base cutting blockprior to attaching the first modular cutting block to the anterior sideof the base cutting block, and resecting a fourth portion of the distalend of the femur using a cutting guide defined in the third modularcutting block that extends transverse to the imaginary plane defined bythe base cutting guide.

In some embodiments, resecting the third portion of the distal end ofthe femur may include advancing a cutting saw blade into contact withthe distal end of the femur along a first cutting guide surfaceextending transverse to the imaginary plane defined by the base cuttingguide, and advancing the cutting saw blade into contact with the distalend of the femur along a second cutting guide surface extendingtransverse to the imaginary plane and orthogonal to the first cuttingguide surface.

Additionally, in some embodiments, the method may include resecting afourth portion of the distal end of the femur using a chamfer cuttingguide defined in the second modular cutting block. The chamfer cuttingguide may extend obliquely relative to the imaginary plane defined bythe base cutting guide.

In some embodiments, the method may include selecting the base cuttingguide from a plurality of base cutting guides defined in the basecutting block. In some embodiments, positioning the base cutting blockand the intramedullary adaptor on the distal end of the femur mayinclude rotating the base cutting block and the intramedullary adaptoron the distal end of the femur relative to an intramedullary orthopaedicsurgical instrument positioned in the medullary canal of the femur, andfixing the base cutting block and the intramedullary adaptor relative tothe intramedullary surgical instrument.

In some embodiments, the intramedullary orthopaedic surgical instrumentmay include a stem trial positioned in the medullary canal of the femur.

In some embodiments, the method may further include detaching theintramedullary adaptor from the base cutting block, attaching a guideblock to the base cutting block in place of the intramedullary adaptor,and reaming the distal end of the femur using a passageway defined inthe guide block.

According to another aspect, a method of surgically preparing a distalend of a femur for implantation of a femoral prosthetic componentincludes positioning a base cutting block and an intramedullary adaptoron the distal end of the femur such that a first end of theintramedullary adaptor is received in the medullary canal of the femurand the intramedullary adaptor is secured to the base cutting block,resecting the femur using a posterior cutting guide defined in the basecutting block, attaching an anterior cutting block to an anterior sideof the base cutting block, resecting the femur using an anterior cuttingguide defined in the anterior cutting block, attaching a notch cuttingblock to the anterior side of the base cutting block in place of theanterior cutting block, and resecting the femur using a notch cuttingguide defined in the notch cutting block to form a notch in the femursized to receive a femoral box of the femoral prosthetic component.

In some embodiments, the method may further include resecting the femurusing a chamfer cutting guide defined in the notch cutting block.Additionally, in some embodiments, the method may further includeresecting the femur using a second chamfer cutting guide defined in thebase cutting block.

In some embodiments, the method may also include detaching theintramedullary adaptor from the base cutting block, attaching a guideblock to the base cutting block in place of the intramedullary adaptor,and reaming the distal end of the femur using a passageway defined inthe guide block.

In some embodiments, the method may further include detaching a coverfrom the base cutting block to expose a pair of mounting shafts formedon the anterior side of the base cutting block. In some embodiments,attaching the anterior cutting block to the anterior side of the basecutting block may include positioning the anterior cutting block overthe pair of mounting shafts.

In some embodiments, the method may include attaching a distal cuttingblock to the anterior side of the base cutting block, and resecting thefemur using a distal cutting guide defined in the distal cutting block.

Additionally, in some embodiments, the method may include selecting thedistal cutting guide from a plurality of distal cutting guides definedin the distal cutting block.

According to another aspect, a method of surgically preparing a distalend of a femur for implantation of a femoral prosthetic componentincludes attaching a first end of an intramedullary adaptor to anintramedullary orthopaedic surgical instrument positioned in themedullary canal of the femur, rotating the intramedullary adaptor and abase cutting block on the distal end of the femur relative to theintramedullary surgical instrument, fixing the base cutting block andthe intramedullary adaptor relative to the intramedullary surgicalinstrument, attaching a first modular cutting block to an anterior sideof the base cutting block, resecting the femur using an anterior cuttingguide defined in the first modular cutting block, attaching a secondmodular cutting block to the anterior side of the base cutting block inplace of the first modular cutting block, and resecting the femur usingan anterior chamfer cutting guide defined in the second modular cuttingblock.

In some embodiments, the method may further include attaching a thirdmodular cutting block to the anterior side of the base cutting blockprior to attaching the first modular cutting block to the base cuttingblock, selecting a distal cutting guide from a plurality of distalcutting guides defined in the third modular cutting block, and resectingthe femur using the distal cutting guide selected from the plurality ofdistal cutting guides.

According to another aspect, a method for performing an orthopaedicsurgical procedure on a femur includes positioning a distal end of anintramedullary adaptor in a slot defined in a base cutting block,securing the distal end of the intramedullary adaptor to the basecutting block, attaching a proximal end of the intramedullary adaptor toan intramedullary orthopaedic surgical instrument after securing theintramedullary adaptor to the base cutting block, and positioning thebase cutting block on a distal end of the femur.

In some embodiments, the method may include advancing the intramedullaryorthopaedic surgical instrument through an opening defined in the distalend of the femur into the medullary canal after attaching theintramedullary adaptor to the intramedullary surgical instrument. Insome embodiments, the method may further include securing a stem trialto a stem stabilizer to form the intramedullary orthopaedic surgicalinstrument.

Additionally, in some embodiments, the stem stabilizer may have aplurality of fins extending outwardly therefrom, and advancing theintramedullary orthopaedic surgical instrument into the medullary canalmay include engaging the plurality of fins with bone surrounding themedullary canal.

In some embodiments, attaching the proximal end of the intramedullaryadaptor to the intramedullary orthopaedic surgical instrument mayinclude threading a shaft of the intramedullary adaptor into aninternally-threaded distal end of the intramedullary surgicalinstrument. In some embodiments, securing the distal end of theintramedullary adaptor to the base cutting block may include advancing alocking tab of the base cutting block into a channel defined in theintramedullary adaptor.

In some embodiments, the method may further include attaching a modularcutting block to an anterior surface of the base cutting block, andresecting the femur using a cutting guide defined in the modular cuttingblock.

In some embodiments, the method may further include assessing a gapdefined between the base cutting block attached to the femur and atibial component attached to a corresponding tibia. In some embodiments,assessing the gap may include selecting a shim from a plurality ofshims, attaching the shim to an end of a handle, and advancing the shimand the end of the handle into contact with the base cutting block andthe tibial component.

Additionally, in some embodiments, the method may include permittingrelative axial rotation between the proximal end of the intramedullaryadaptor and the intramedullary orthopaedic surgical instrument. In someembodiments, the relative axial rotation is limited by a lug extendingfrom the intramedullary adaptor.

According to another aspect, the method includes securing a stem trialto a stem stabilizer to form an intramedullary orthopaedic surgicalinstrument, securing a proximal end of an intramedullary adaptor to adistal end of the stem stabilizer, positioning a mounting bracket of theintramedullary adaptor in a slot defined in a base cutting block,placing a locking tab of the base cutting block in a channel defined inthe mounting bracket of the intramedullary adaptor, advancing theintramedullary orthopaedic surgical instrument and the proximal end ofthe intramedullary adaptor through an opening defined in a distal end ofthe femur, and positioning the base cutting block on the distal end ofthe femur.

In some embodiments, securing the proximal end of an intramedullaryadaptor to the distal end of the stem stabilizer may include aligning ashaft of the intramedullary adaptor with an aperture defined in thedistal end of the stem stabilizer, and rotating the shaft of theintramedullary adaptor in a first direction to advance the shaft intothe aperture and prevent an adaptor body of the intramedullary adaptorfrom moving relative to the stem stabilizer.

In some embodiments, the method may include rotating the shaft of theintramedullary adaptor in a second direction opposite the firstdirection to permit the adaptor body to rotate relative to the stemstabilizer, and rotating the intramedullary adaptor and the base cuttingblock relative to the stem stabilizer.

In some embodiments, the method may further include selecting a shimhaving a predetermined thickness from a plurality of shims, attachingthe shim to a handle, and inserting the shim and the handle between thebase cutting block and a tibial component secured to a proximal end of atibia. Rotating the intramedullary adaptor and the base cutting blockmay be performed after the shim and the handle are inserted.

In some embodiments, the method may further include assessing a gapdefined between the base cutting block and a tibial component.

According to another aspect, the method may include attaching a proximalend of an intramedullary adaptor to an intramedullary orthopaedicsurgical instrument, securing a distal end of an intramedullary adaptorto a base cutting block, inserting the intramedullary orthopaedicsurgical instrument into a medullary canal using the base cutting block,and positioning the base cutting block on a distal end of the femur. Insome embodiments, the method may further include attaching a modularcutting block to an anterior surface of the base cutting block, andresecting the femur using a cutting guide defined in the modular cuttingblock.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is an exploded view of an exemplary embodiment of an orthopaedicsurgical instrument assembly;

FIG. 2 is a perspective view of a base cutting block of the instrumentassembly of FIG. 1;

FIG. 3 is a side elevation view of the base cutting block of FIG. 2;

FIG. 4 is a perspective view of an anterior cutting block of theinstrument assembly of FIG. 1;

FIG. 5 is a cross-sectional side elevation view of the anterior cuttingblock of FIG. 4;

FIG. 6 is a perspective view of a notch cutting block of the instrumentassembly of FIG. 1;

FIG. 7 is a perspective view of a distal cutting block of the instrumentassembly of FIG. 1;

FIG. 8 is a perspective view of an intramedullary adaptor of theinstrument assembly of FIG. 1;

FIG. 9 is a cross-sectional side elevation view of the intramedullaryadaptor of FIG. 8;

FIG. 10 is a perspective view of one embodiment of a stem stabilizerconfigured to be coupled to the intramedullary adaptor of FIG. 8;

FIG. 11 is plan view of the stem stabilizer of FIG. 10;

FIG. 12 is a perspective view of another embodiment of a stem stabilizerconfigured to be coupled to the intramedullary adaptor of FIG. 8;

FIG. 13 is a perspective view of one embodiment of a guide blockconfigured to be coupled to the base cutting block of FIG. 2;

FIG. 14 is a perspective view of another embodiment of a guide blockconfigured to be coupled to the base cutting block of FIG. 2;

FIG. 15 is a perspective view of a distal spacer block configured to becoupled to the base cutting block of FIG. 2;

FIG. 16 is a perspective view of a shim configured to be coupled to thebase cutting block of FIG. 2;

FIG. 17 is a side elevation view of the shim of FIG. 16;

FIG. 18 is a perspective view of a gap assessment tool;

FIGS. 19A and 19B are a simplified flow chart of a procedure for usingthe orthopaedic surgical instruments of FIGS. 1-18; and

FIGS. 20-32 are views of a patient's femur and the orthopaedic surgicalinstruments of FIGS. 1-18 as the orthopaedic surgical instruments areused in the procedure of FIG. 19.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior,medial, lateral, superior, inferior, etcetera, may be used throughoutthe specification in reference to the orthopaedic implants andorthopaedic surgical instruments described herein as well as inreference to the patient's natural anatomy. Such terms havewell-understood meanings in both the study of anatomy and the field oforthopaedics. Use of such anatomical reference terms in the writtendescription and claims is intended to be consistent with theirwell-understood meanings unless noted otherwise.

Referring now to FIG. 1, an orthopaedic surgical instrument assembly 10(hereinafter instrument assembly 10) is shown. What is meant herein bythe term “orthopaedic surgical instrument” or “orthopaedic surgicalinstrument assembly” is a surgical tool for use by a surgeon inperforming an orthopaedic surgical procedure. As such, it should beappreciated that, as used herein, the terms “orthopaedic surgicalinstrument” and “orthopaedic surgical instruments” are distinct fromorthopaedic implants or prostheses that are surgically implanted in thebody of the patient. The instrument assembly 10 includes a base cuttingblock 12 configured for use on a femur of a patient, as described ingreater detail below.

The instrument assembly 10 also includes a plurality of modular cuttingblocks 14 configured to be coupled to the base cutting block 12. In theillustrative embodiment, the modular cutting blocks 14 include ananterior cutting block 16, a notch cutting block 18, and a distalcutting block 20. As described in greater detail below, each modularcutting block 14 may be secured to the base cutting block 12 in place ofthe other modular cutting blocks 14 during the orthopaedic surgicalprocedure. For example, the anterior cutting block 16 may be secured tothe base cutting block 12 at one point during the orthopaedic surgicalprocedure, and the notch cutting block 18 or the distal cutting block 20may be secured to the base cutting block 12 in place of the anteriorcutting block 16 at other points during the orthopaedic surgicalprocedure.

The instrument assembly 10 includes a locking or retention mechanism 22that secures each modular cutting block 14 to the base cutting block 12.In the illustrative embodiment, the retention mechanism 22 includes apair of mounting brackets 24 attached to the base cutting block 12 and apair of mounting brackets 26 attached to the modular cutting block 14.As described in greater detail below, the mounting brackets 26 of amodular cutting block 14 are configured to engage the mounting brackets24 of the base cutting block 12 when the modular cutting block 14 issecured to the base cutting block 12, thereby securing the blockstogether. The instrument assembly 10 also includes a cover 28, which maybe positioned over the mounting brackets 24 of the base cutting block 12when none of the modular cutting blocks 14 are secured to the basecutting block 12.

As shown in FIG. 1, the instrument assembly 10 also includes anintramedullary adaptor 30 configured to be coupled to the base cuttingblock 12. What is meant herein by the term “intramedullary adaptor” is asurgical tool configured to be secured to an intramedullary orthopaedicsurgical instrument and including an end sized and shaped to bepositioned in a medullary canal of a patient's femur during theorthopaedic surgical procedure. What is meant herein by the term“intramedullary orthopaedic surgical instrument” is a surgical toolconfigured to be positioned in the medullary canal of the patient'sfemur during the orthopaedic surgical procedure. Examples ofintramedullary orthopaedic surgical instruments include femoral stemtrials, femoral broaches, and the like. The instrument assembly 10includes a locking mechanism 32 that secures the intramedullary adaptor30 to the base cutting block 12, as described in greater detail below.

Referring now to FIGS. 2 and 3, the base cutting block 12 includes abase plate 40 and a pair of arms 42 extending from the base plate 40.The base plate 40 and the arms 42 of the base cutting block 12 areformed from a metallic material, such as, for example, a stainless steelor a cobalt chromium alloy. The base plate 40 includes a distal surface44 and a proximal surface 46 positioned opposite the distal surface 44.An opening 48 is defined in the distal surface 44, and an inner wall 50extends distally through the base plate 40 to define a receiving slot52. As described in greater detail below, the slot 52 is sized to permitthe passage of the intramedullary adaptor 30 and various other surgicaltools.

The base cutting block 12 also includes a pair of fastener guides 54that are defined in the base plate 40. Each fastener guide 54 includes abore 56 that is sized to receive fasteners such as, for example,fixation pins 58 (see FIG. 24), which may be utilized to secure the basecutting block 12 to the patient's femur. It should be appreciated thatin other embodiments the base cutting block 12 may include additionalfastener guides 54 or other fastening elements to secure the cuttingblock to the patient's femur.

The arms 42 of the base cutting block 12 extends posteriorly from aposterior side 60 of the base cutting block 12. Each arm 42 includes anarticulating surface 62 shaped to match a condylar surface of a femoralprosthetic component. In that way, the articulating surfaces 62 of thearms 42 are configured to contact a natural or prosthetic bearingsurface of the patient's tibia. The arms 42 are spaced apart such thatan opening 64 is defined therebetween.

The base cutting block 12 includes a number of cutting guides 66 thatmay be used during an orthopaedic surgical procedure to resect a portionof a patient's femur. For example, as shown in FIG. 2, the base cuttingblock 12 includes a number of posterior cutting guides 68 defined in thearms 42 and a posterior chamfer cutting guide 70 defined in the baseplate 40. Each cutting guide 66 includes an elongated slot sized toreceive a cutting saw blade of a surgical saw or other surgical device.

In the illustrative embodiment, each arm 42 has three posterior cuttingguides 68 defined in the articulating surface 62 thereof. Each posteriorcutting guide 68 includes a planar surface 72 that extends inwardly fromthe articulating surface 62. Each planar surface 72 defines a resectionplane 74 that extends through a portion of the posterior condyles of thepatient's femur when the base cutting block 12 is positioned thereon. Inthat way, the cutting guides 68 may be used by the orthopaedic surgeonduring the resection of the patient's femur. As shown in FIG. 3, theresection planes 74 of the cutting guides 68 extend parallel to, and arespaced from, each other. In the illustrative embodiment, the cuttingguides 68 are spaced apart from each other by about four millimeters. Itshould be appreciated that in other embodiments the arms 42 may includeadditional or fewer cutting guides 66 to provide the surgeon with otherresection planes.

As shown in FIG. 2, the posterior chamfer cutting guide 70 defined inthe base plate 40 includes a planar surface 76 that extends inwardlyfrom the distal surface 44. The planar surface 76 defines a resectionplane 78 that extends through a portion of the posterior condyles of thepatient's femur when the base cutting block 12 is positioned thereon. Inthat way, the cutting guides 68 may be used by the orthopaedic surgeonduring the resection of the patient's femur. As shown in FIG. 3, theresection plane 78 of the posterior chamfer cutting guide 70 extendsobliquely relative to the resection planes 74 defined by the posteriorcutting guides 68 such that an obtuse angle is defined between theplanes 74, 78. In other embodiments, the base cutting block 12 may alsoinclude an anterior chamfer cutting guide positioned opposite theposterior chamfer cutting guide 70.

As described above, the instrument assembly 10 includes a retentionmechanism 22, and the base cutting block 12 has a pair of mountingbrackets 24 of that retention mechanism 22. As shown in FIGS. 2 and 3,each mounting bracket 24 includes a hub 80 attached to the anterior sidesurface 82 of the base cutting block 12 and a shaft 84 that extendsanteriorly from the hub 80. A flange 86 extends outwardly from eachshaft 84, and each flange 86 includes an anterior cam surface 88 and aposterior surface 90. A recess 92 is defined between is defined betweenthe posterior surface 90 of each flange 86 and each hub 80. As describedin greater detail below, the recesses 92 of the mounting brackets 24 aresized to receive catches 94 of the mounting brackets 26 of a modularcutting block 14 to secure the block 14 to the base cutting block 12.

As described above, the instrument assembly 10 includes a lockingmechanism 32 to secure the intramedullary adaptor 30 to the base cuttingblock 12. In the illustrative embodiment, the locking mechanism 32includes a pair of locking tabs 100, 102 pivotally coupled to the basecutting block 12. As shown in FIG. 1, the inner wall 50 of the basecutting block 12 has an aperture 104 defined therein, and the lockingtab 100 is positioned in the aperture 104. The locking tab 100 iscoupled to the base cutting block 12 via a joint 106. The joint 106includes a pin 108 that extends from the locking tab 100 and is receivedin a bore 110 defined in the distal surface 44 of the base plate 40. Thelocking tab 100 is configured to pivot about an axis 112 defined by thepin 108 between a locked position (see FIG. 1) and an unlocked position(see FIG. 2). In the locked position, an ear 114 of the locking tab 100is positioned in the receiving slot 52 of the base cutting block 12 tothereby engage a surgical instrument (e.g., the intramedullary adaptor30) positioned in the slot 52. In the unlocked position, the ear 114 ispositioned in the aperture 104 and spaced apart from the receiving slot52.

The inner wall 50 of the base cutting block 12 has another aperture 116defined therein opposite the aperture 104. The locking tab 102 ispositioned in the aperture 116 and is coupled to the base cutting block12 via a joint 118. The joint 118 includes a pin 120 that extends fromthe locking tab 102 and is received in a bore 122 defined in the distalsurface 44 of the base plate 40. The locking tab 102 is configured topivot about an axis 124 defined by the pin 120 between a locked position(see FIG. 2) and an unlocked position (see FIG. 1). In the lockedposition, an ear 126 of the locking tab 102 is positioned in thereceiving slot 52 of the base cutting block 12 to thereby engage asurgical instrument (e.g., the intramedullary adaptor 30) positioned inthe slot 52. In the unlocked position, the ear 126 is positioned in theaperture 116 and spaced apart from the receiving slot 52.

As shown in FIG. 2, each pin 108, 120 of the locking mechanism 32 has asocket 128 defined in an outer surface thereof. The sockets 128 areaccessible through the bores 110, 122 of the base plate 40, and eachsocket 128 is sized and shaped to receive a corresponding end of asurgical tool. In an orthopaedic surgical procedure, a surgeon mayinsert the surgical tool into the socket 128 to move the respectivelocking tab 100, 102 between the locked position and the unlockedposition. It should be appreciated that in other embodiments the lockingmechanism may include threaded fasteners, latches, pins, or otherstructures necessary to secure the base cutting block 12 to anothersurgical instrument.

As shown in FIG. 3, the base plate 40 of the base cutting block 12 has aside wall 132 that extends between the distal surface 44 and theproximal surface 46. The side wall 132 has an opening 134 definedtherein, and an inner wall 136 extends inwardly from the opening 134 todefine a channel 138 in the proximal surface 46. The channel 138includes a cylindrical segment 140 that is sized to receive acorresponding cylindrical pin 142, as described in greater detail below.The channel 138 is aligned with one of the fastener guides 54 such thatthe bore 56 of the fastener guide 54 opens into the cylindrical segment140. The base plate 40 has another side wall 144 that is positionedopposite the side wall 132. Another channel (not shown) that is themirror of the channel 138 extends inwardly from an opening defined inthe side wall 144.

As described above, the instrument assembly 10 includes a number ofmodular cutting blocks 14 configured to be secured to the base cuttingblock 12. Each of the modular cutting blocks 14 is formed from ametallic material, such as, for example, a stainless steel or a cobaltchromium alloy. Referring now to FIGS. 4 and 5, the modular cuttingblocks 14 include an anterior cutting block 16. The anterior cuttingblock 16 includes a posterior side wall 150 that confronts the anteriorside surface 82 of the base cutting block 12 when the anterior cuttingblock 16 is secured to the block 12. An alignment pin 146 extendsoutwardly from the posterior side wall 150, and that pin 146 is receivedin an aperture 148 defined in the base cutting block 12 (see FIG. 2).The anterior cutting block 16 also includes an anterior side wall 152that is positioned opposite the posterior side wall 150. A distalsurface 154 extends between the side walls 150, 152.

The anterior cutting block 16 includes an anterior cutting guide 156that may be used during an orthopaedic surgical procedure to resect ananterior portion of the patient's femur. The anterior cutting guide 156includes an elongated slot 158 that extends inwardly from an opening 160defined in the distal surface 154. The elongated slot 158 is sized toreceive a cutting saw blade of a surgical saw or other surgical device.The cutting guide 156 includes a planar surface 162 that is connected tothe distal surface 154, and the planar surface 162 defines a resectionplane 164 that extends through an anterior portion of the patient'sfemur when the anterior cutting block 16 is secured to the base cuttingblock 12 on the patient's femur.

As described above, the instrument assembly 10 includes a retentionmechanism 22 configured to secure each modular cutting block 14 to thebase cutting block 12. Each modular cutting block 14 has a pair ofmounting brackets 26 configured to engage the mounting brackets 24 ofthe base cutting block 12, thereby securing the modular cutting block 14to the block 12. As shown in FIG. 5, each mounting bracket 26 includes alever arm 166 pivotally coupled to the modular cutting block 14 (in thiscase, the anterior cutting block 16). The lever arm 166 includes a leverbody 168 pivotally coupled to the modular cutting block 14 via a joint170. The joint 170 includes a cylindrical pin 172 that extends through amounting hole 174 defined in the lever body 168. Each end (not shown) ofthe pin 172 is received in an aperture defined in the modular cuttingblock. The pin 172 defines an axis 176 about which the lever arm 166 maypivot.

As shown in FIG. 5, the lever body 168 of the arm 166 is positioned in apassageway 180 extending through the modular cutting block 14. A handle182 is formed on one end of the lever body 168 and extends outwardlyfrom the passageway 180. A catch 94 is formed on the opposite end of thelever body 168. As described above, the catch 94 is received in one ofthe recesses 92 defined in the mounting brackets 24 of the base cuttingblock 12. The catch 94 includes an engagement surface 184 that engages aposterior surface 90 of the mounting brackets 24 to secure the modularcutting block 14 to the base cutting block 12.

As described above, the lever arm 166 is configured to pivot about theaxis 176, and is moveable between an engaged position (see left side ofFIG. 5) and a disengaged position (see right side of FIG. 5). Themounting bracket 26 also includes a biasing element 190 that biases thelever arm 166 is the engaged position. As shown in FIG. 5, the biasingelement 190 is a cantilever spring having an end 192 attached to thelever arm 166 and another end 194 engaged with an inner wall 196 of themounting bracket 26. It should be appreciated that in other embodimentsthe biasing element 190 may be, for example, a coil, torsion, or otherspring.

In use, a surgeon or other user grasps the handles 182 of the lever arms166 and pushes in the direction indicated by arrow 200. When the biasexerted by the springs 190 is overcome, the lever arm 166 is pivotedabout the axis 176 from the engaged position to the disengaged position.The shafts 84 of the base cutting block 12 may then be aligned with thepassageways 180 defined in the modular cutting block 14. The modularcutting block 14 may then be advanced over the shafts 84 such that themodular cutting block 14 confronts the anterior side surface 82 of thebase cutting block 12. The surgeon may then release the handles 182,thereby permitting the lever arms 166 to pivot back to the engagedposition. In the engaged position, the catch 94 is received in therecess 92 of the mounting brackets 24 of the base cutting block 12 andengages a posterior surface 90 of the mounting bracket 24 to secure themodular cutting block 14 to the base cutting block 12.

It should be appreciated that in other embodiments the retentionmechanism may take other forms. For example, the arrangement of shaftsand locking arms may be reversed with the base cutting block beconfigured to receive the shafts extending from the modular cuttingblocks. In other embodiments, each modular cutting block may include anumber of locking pins that may be extended and retracted to attach anddetach the modular cutting block to the base cutting block. In stillother embodiments, the retention mechanism may include an external latchon one block that engages a pin or flange on the block.

Referring now to FIG. 6, the modular cutting blocks 14 include a notchcutting block 18. The notch cutting block 18 includes a posterior sidewall 202 that confronts the anterior side surface 82 of the base cuttingblock 12 when the notch cutting block 18 is secured to the block 12. Thenotch cutting block 18 also includes an anterior side wall 204 that ispositioned opposite the posterior side wall 202. As described above, thenotch cutting block 18 includes a pair of mounting brackets 26 of theretention mechanism 22, which are configured to secure the notch cuttingblock 18 to the base cutting block 12.

The notch cutting block 18 includes a notch cutting guide 206 that maybe used during an orthopaedic surgical procedure to form a notch in thepatient's femur sized to receive a femoral box of the femoral prostheticcomponent. As shown in FIG. 6, the notch cutting block 18 has an opening208 defined in the anterior side wall 204, and an inner wall 210 extendsposteriorly from the opening 208 to define the notch cutting guide 206in the block 18. The inner wall 210 includes a planar surface 212 thatdefines a resection plane 214, which extends through a portion of thepatient's femur when the notch cutting block 18 is secured to the basecutting block 12 on the patient's femur. In the illustrative embodiment,the resection plane 214 of the notch cutting guide 206 extendsorthogonal to the resection planes 74 defined by the posterior cuttingguides 68 of the base cutting block 12 when the notch cutting block 18is secured to the block 12.

The inner wall 210 of the notch cutting block 18 also includes a pair ofplanar surfaces 216 that are connected to the planar surface 212 andextend transverse to the resection plane 214 defined by the surface 212.Each surface 216 defines a resection plane 218 that extends orthogonalto the resection planes 74 defined by the posterior cutting guides 68 ofthe base cutting block 12 when the notch cutting block 18 is secured tothe block 12. The surfaces 212, 216 define a channel 220 of the notchcutting guide 206 sized to receive a surgical saw blade or othersurgical instrument.

As shown in FIG. 6, the notch cutting block 18 also includes an anteriorchamfer cutting guide 222. The anterior chamfer cutting guide 222includes an elongated slot 224 that extends inwardly from an openingdefined in the anterior side wall 204. The elongated slot 224 is sizedto receive a cutting saw blade of a surgical saw or other surgicaldevice. The cutting guide 222 includes a planar surface 226 that definesa resection plane 228. The resection plane 228 extends through ananterior portion of the patient's femur when the notch cutting block 18is secured to the base cutting block 12 on the patient's femur. When theblocks 12, 18 are assembled, the resection plane 228 of the anteriorchamfer cutting guide 222 extends obliquely relative to the resectionplanes 74 defined by the posterior cutting guides 68 such that an obtuseangle is defined between the planes 74, 228.

As shown in FIG. 6, a pair of fastener guides 230 are pivotally coupledto the notch cutting block 18. Each guide 230 includes a cylindricalbody 232, and a bore 234 is defined in the body 232. The bore 234 issized to receive fasteners such as, for example, fixation pins 58 (seeFIG. 24), which may be utilized to secure the notch cutting block 18 tothe patient's femur. It should be appreciated that in other embodimentsthe notch cutting block 18 may include additional fastener guides 230 orother fastening elements to secure the cutting block to the patient'sfemur.

Each cylindrical body 232 extends outwardly through a hole 238 definedin the anterior side wall 204 of the notch cutting block 18. Eachfastener guide 230 also includes a hub 240 that is pivotally coupled tothe block 18. In that way, the fastener guide 230 may be moved back andforth in the direction indicated by arrow 242 to adjust the orientationof the bore 234 and hence change the location of the fixation pin 58 onthe patient's femur. It should be appreciated that in other embodimentsthe fixation guide 230 may be adjustable in other directions.

Referring now to FIG. 7, the modular cutting blocks 14 include a distalcutting block 20. The distal cutting block 20 includes a posterior sidewall 250 that confronts the anterior side surface 82 of the base cuttingblock 12 when the distal cutting block 20 is secured to the block 12.The distal cutting block 20 also includes an anterior side wall 252 thatis positioned opposite the posterior side wall 250. As described above,the distal cutting block 20 includes a pair of mounting brackets 26 ofthe retention mechanism 22, which are configured to secure the distalcutting block 20 to the base cutting block 12.

The distal cutting block 20 includes a number of distal cutting guides256 that may be used during an orthopaedic surgical procedure to resecta distal portion of the patient's bone. Each cutting guide 256 includesan elongated slot sized to receive a cutting saw blade of a surgical sawor other surgical device. In the illustrative embodiment, the distalcutting block 20 has ten distal cutting guides 256 extending through theside walls 250, 252. Each distal cutting guide 256 includes a planarsurface 258 that defines a resection plane 260. As shown in FIG. 7, theresection planes 260 of the cutting guides 256 extend parallel to, andare spaced from, each other. In the illustrative embodiment, theresection planes 260 of the distal cutting block 20 extends orthogonalto the resection planes 74 defined by the posterior cutting guides 68 ofthe base cutting block 12 when the distal cutting block 20 is secured tothe block 12.

The resection planes 260 extend through a distal portion of thepatient's femur when the distal cutting block 20 is secured to the basecutting block 12 on the femur. In that way, the cutting guides 256 maybe used by the orthopaedic surgeon during the resection of the patient'sfemur. In the illustrative embodiment, the cutting guides 256 (hence theresection planes 260) are spaced part from each other by about fourmillimeters. As such, the surgeon may select the particular cuttingguide 256 corresponding to the amount of bone to be removed. In otherembodiments, the distal cutting block 20 may include any number ofcutting guides 256, which may be spaced apart by an amount greater thanor less than four millimeters.

As shown in FIG. 7, a pair of fastener guides 262 are pivotally coupledto the distal cutting block 20. Each guide 262 includes a cylindricalbody 264, and a bore 266 is defined in the body 264. The bore 266 issized to receive fasteners such as, for example, fixation pins 58 (seeFIG. 26), which may be utilized to secure the distal cutting block 20 tothe patient's femur. It should be appreciated that in other embodimentsthe distal cutting block 20 may include additional fastener guides 262or other fastening elements to secure the cutting block to the patient'sfemur.

Each cylindrical body 264 extends outwardly through a hole 268 definedin the anterior side wall 252 of the distal cutting block 20. Eachfastener guide 262 also includes a hub 270 that is pivotally coupled tothe block 20. In that way, the fastener guide 262 may be moved back andforth in the direction indicated by arrow 272 to adjust the orientationof the bore 266 and hence change the location of the fixation pin 58 onthe patient's femur. It should be appreciated that in other embodimentsthe fastener guide 262 may be adjustable in other directions.

Referring now to FIGS. 8 and 9, the instrument assembly 10 includes anintramedullary adaptor 30 configured to be coupled to the base cuttingblock 12. The intramedullary adaptor 30 is formed from a metallicmaterial, such as, for example, a stainless steel or a cobalt chromiumalloy. The intramedullary adaptor 30 includes a mounting bracket 280attached to a main body 282. As will be described in greater detailbelow, the mounting bracket 280 is sized to be positioned in thereceiving slot 52 of the base cutting block 12. The mounting bracket 280includes a pair of arms 284, 286 extending outwardly from the main body282 to respective ends 288, 290. A channel 292 is defined in the end 288of the arm 284, and the channel 292 is sized to receive the ear 114 ofthe locking tab 100 or the ear 126 of the locking tab 102 of the basecutting block 12. Another channel 294 is defined in the end 290 of theother arm 286. The channel 294 is also sized to receive the ear 114 ofthe locking tab 100 or the ear 126 of the locking tab 102 of the basecutting block 12.

As shown in FIG. 8, the mounting bracket 280 has a substantially planardistal surface 296. The main body 282 of the adaptor 30 has alongitudinal axis 298 that extends obliquely relative to the distalsurface 296. The main body 282 has a proximal end 300, and a pair ofalignment lugs 302 extend outwardly from the proximal end 300 of thebody 282. The main body 282 is sized and shaped to be received in themedullary canal of the patient's femur, as described in greater detailbelow.

The adaptor 30 also includes a fastener 304 configured to secure theadaptor 30 to an intramedullary surgical instrument, as described ingreater detail below. The fastener 304 is positioned in a passageway 306defined in the body 282 and is configured to rotate relative to the mainbody 282. A retaining ring 308 is secured to the proximal end 300 of themain body 282, thereby securing the fastener 304 to the main body 282.

Referring now to FIG. 9, the fastener 304 includes a head 310 positionedin the passageway 306 and a shaft 312 extending through the retainingring 308 and outwardly from the body 282 to a proximal end 314. Theproximal end 314 of the shaft 312 has a plurality of external threads316 formed thereon. The head 310 of the fastener 304 has a socket 318defined therein. In an orthopaedic surgical procedure, a surgeon mayinsert the surgical tool into the socket 318 to rotate the fastener 304relative to the main body 282.

Referring now to FIGS. 10-18, a number of other surgical instruments foruse with the instrument assembly 10 are shown. In FIGS. 10 and 11, oneembodiment of a stem stabilizer 320 is shown. The stem stabilizer 320 isformed from a metallic material, such as, for example, a stainless steelor a cobalt chromium alloy. The stem stabilizer 320 includes acylindrical body 322 extending from an end 324 configured to confrontthe proximal end 300 of the main body 282 of the adaptor 30 to an end326 configured to confront the distal end of a stem trial 328 (see FIG.20). The end 324 of the body 322 has an opening 330 defined therein, anda central passageway 332 extends inwardly from the opening 330 throughthe body 322. The central passageway 332 is sized to receive the shaft312 of the intramedullary adaptor 30. A cylindrical inner wall 334defines the passageway 332, and the inner wall 334 has a plurality ofinternal threads 338 formed thereon that correspond to the externalthreads 316 formed on the shaft 312 and the external threads (not shown)formed on the stem trial 328. When the stem trial 328 is secured to thestem stabilizer 320, an intramedullary orthopaedic surgical instrument336 is formed (see FIG. 20), as described in greater detail below.

As shown in FIG. 11, a pair of slots 340 extend inwardly from theopening 330 on either side of the central passageway 332. Each slot 340is arcuate in shape and is defined by a pair of substantially planarinner walls 342, 344 and an arcuate inner wall 346 extending between theinner walls 342, 344. As will be described in greater detail below, onealignment lug 302 of the intramedullary adaptor 30 is positioned in eacharcuate slot 340 when the intramedullary adaptor 30 is secured to thestem stabilizer 320.

Each arcuate inner wall 346 defines an arc 348. The magnitude of the arc348 is dependant on the permitted rotation of the femoral prostheticcomponent and therefore varies depending on the choice of prostheticcomponent.

Referring now to FIG. 12, another embodiment of a stem stabilizer(hereinafter stem stabilizer 350) is shown. The stem stabilizer 350includes a cylindrical body 352 extending from an end 324 configured toconfront the proximal end 300 of the main body 282 of the adaptor 30 toan end 326 configured to confront the distal end of a stem trial 328(see FIG. 20). A medial fin 354 and a lateral fin 356 extend outwardlyfrom an outer surface 358 of the cylindrical body 352. Each of the fins354, 356 includes an outer edge 360 configured to engage the patient'sfemur when the stem stabilizer 350 is positioned in the medullary canal.In that way, the fins 354, 356 may provide additional stability duringan orthopaedic surgical procedure. It should be appreciated that inother embodiments the stem stabilizer may include additional fins havingdifferent sizes and different configurations.

Like the stem stabilizer 350, the end 324 of the body 352 has an opening330 defined therein, and a central passageway 332 extends inwardly fromthe opening 330 through the body 352. The central passageway 332 issized to receive the shaft 312 of the intramedullary adaptor 30. Acylindrical inner wall 334 defines the passageway 332, and the innerwall 334 has a plurality of internal threads 338 formed thereon thatcorrespond to the external threads 316 formed on the shaft 312. A pairof arcuate slots 340 extend inwardly from the opening 330 on either sideof the central passageway 332.

Referring now to FIG. 13, a guide block 362 is shown. The guide block362 is configured to be secured to the base cutting block 12 in place ofthe intramedullary adaptor 30. The guide block 362 is formed from ametallic material, such as, for example, a stainless steel or a cobaltchromium alloy. The guide block 362 includes a mounting bracket 364attached to a bushing 366. As will be described in greater detail below,the mounting bracket 364 is sized to be positioned in the receiving slot52 of the base cutting block 12. The mounting bracket 364 includes apair of arms 368 extending outwardly from the bushing 366 to respectiveends 370. A channel 372 is defined in each end 370 of the arm 368. Thechannel 372 is sized to receive the ear 114 of the locking tab 100 orthe ear 126 of the locking tab 102 of the base cutting block 12.

The bushing 366 of the guide block 362 has an opening 374 defined in adistal end 376 thereof. A cylindrical inner wall 378 extends inwardlyfrom the distal end 376 to define a passageway 380 through the bushing366. The passageway 380 is sized to permit the passage of a surgicaldrill or reamer. In that way, the block 362 guides the surgical drill orreamer during the orthopaedic surgical procedure.

As shown in FIG. 13, the passageway 380 has a longitudinal axis 382. Themounting bracket 364 has a substantially planar distal surface 384. Inthe illustrative embodiment, an oblique angle is defined between thelongitudinal axis 382 and the substantially planar proximal surface 384.

It should be appreciated that in other embodiments the passageway 380 ofthe guide block 362 may be resized to accommodate various types ofsurgical drills or reamers. For example, as shown in FIG. 14, anotherembodiment of a guide block 386 includes a passageway 388 that has asmaller diameter than the passageway 380. Additionally, the angledefined between the longitudinal axis of the passageway and the distalsurface 384 of the mounting bracket 364 may also vary. In otherembodiments, the length of the bushing may also vary.

Referring now to FIG. 15, a distal spacer block 390 is shown. The block390 is configured to be secured to base cutting block 12 between theproximal surface 46 of the plate 40 and a distal end of the patient'sfemur. The distal spacer block 390 is formed from a metallic material,such as, for example, a stainless steel or a cobalt chromium alloy. Thespacer block 390 may be one of a plurality of spacer blocks havingdifferent sizes and corresponding to different prosthetic augment sizes.

The block 390 includes a plate 394 and a pin 396 secured to the plate394. The plate 394 includes pair of grips 398 formed on each side 400thereof. A surgeon may grasp the grips 398 to insert the block 390between the base cutting block 12 and the patient's femur. As shown inFIG. 5, the pin 396 of distal spacer block 390 includes a cylindricalshaft 402 sized to be received in the channel 138 defined in the basecutting block 12. The shaft 402 has an outer diameter that is greaterthan the inner diameter of the cylindrical segment 140 of the channel138 such that the distal spacer block 390 is secured to the base cuttingblock 12 via friction.

The distal spacer block 390 also includes a stop 404 secured to theplate 394. The stop 404 includes a flange 406 that confronts one of theside wall 132, 144 of the base cutting block 12 when the distal spacerblock 390 is properly positioned. The stop 404 also includes a grip 408,which the surgeon may use to withdraw the block 390 from between thebase cutting block 12 and the patient's femur. An indicator (not shown)may be etched into the outer surface 410 of the stop 404 to indicate thesize of the spacer block 390.

The spacer block 390 also includes a bore 412 that is defined in theplate 394. As shown in FIG. 15, the bore 412 divides the pin 396 intotwo sections 414, 416. When the distal spacer block 390 is properlypositioned, the bore 412 is axially aligned with the guide bore 56 ofthe fastener guide 54. When a fixation pin 58 is inserted into thefastener guide 54 while the distal spacer block 390 is secured to thebase cutting block 12, the pin 58 is advanced through the guide bore 56and the bore 412 into the patient's femur.

Referring now to FIGS. 16 and 17, a posterior shim 420 is shown. Theposterior shim 420 is configured to be positioned in one of the cuttingguides 68 defined in the base cutting block 12 during a surgicalprocedure. The posterior shim 420 is formed from a metallic material,such as, for example, a stainless steel or a cobalt chromium alloy. Theposterior shim 420 includes a body 422 sized to be positioned in acutting guide 68 and a grip 424 that may be grasped by the surgeon toposition the posterior shim 420 in the cutting guide 68.

The posterior shim 420 also includes a stop 426 positioned between thebody 422 and the grip 424. The stop 426 includes a flange 428 thatconfronts the articulating surface 62 of one of the arms 42 of the basecutting block 12. A cantilevered spring 430 is secured to the body 422of the posterior shim 420. The cantilevered end 432 of the spring 430 isconfigured to engage the side walls of the cutting guide 68 to retainthe posterior shim 420 in position.

Referring now to FIG. 18, a gap assessment tool 434 is shown. The gapassessment tool 434 includes a handle 436 and a plurality of shim blocks438 configured to be secured to the handle 436. Only a single shim block438 is shown in FIG. 18. The handle 436 has a spacer end 440, a spacerend 442 positioned opposite the spacer end 440, and a body 444connecting the ends 440, 442. The handle 436 is formed from a metallicmaterial, such as, for example, a stainless steel or a cobalt chromiumalloy. It should also be appreciated that the handle 436 may be formedfrom a hard polymeric material. The body 444 includes a grip 446 thatmay be utilized by the surgeon to manipulate the handle 436.

The spacer end 440 includes a pair of arms 450 extending outwardly fromthe body 444 of the handle 436. Each arm 450 has a bore 452 definedtherein, and an opening 454 is defined between the arms 450. The spacerend 440 has a thickness 456 that corresponds to the thickness of atibial trial. Similarly, the spacer end 442 also includes a pair of arms458 extending outwardly from the body 444 of the handle 436. Each arm458 has a bore 460 defined therein, and an opening 462 is definedbetween the arms 458. The spacer end 442 has a thickness 464 thatcorresponds to the thickness of another tibial trial. In theillustrative embodiment, the thicknesses 456, 464 of the spacer ends440, 442 are different.

Each shim block 438 includes an articulation surface 470 configured toengage the articulating surface 62 of the base cutting block 12. Theshim blocks 438 are formed from a hard polymeric material, such as, forexample, acetal. It should be appreciated that in other embodiments theblocks 438 may be formed from a metallic material, such as, for example,stainless steel or cobalt chromium. The shim block 438 has a pair ofarms 472 that correspond to the arms 450, 458 of the handle 436. Eacharm 472 has a post 474 extending downwardly from a bottom surface 476.Each post 474 is sized to be received in each bore 452, 460 defined inthe handle 436. The shim block 438 may include a spring or otherretention device to secure the shim block 438 to the handle 436.

As described above, the gap assessment tool 434 includes a plurality ofshim blocks 438, each of which may be separately attached to the handle436. Each shim block 438 has a different thickness 478 such that thesurgeon is able to assemble a gap assessment tool of one size andconfiguration, evaluate the performance, and then modify the gapassessment tool as necessary to determine intraoperatively the flexionand extension gaps of the patient, as described in greater detail below.

Returning to FIG. 1, the instrument assembly 10 also includes a cover 28configured to be positioned over the shafts 84 of the base cuttingblock. The cover 28 has a body 480 that includes a substantially planarposterior surface 482. In the illustrative embodiment, the body 480 isformed from a polymeric material, such as, for example, acetal. Itshould be appreciated that in other embodiments the cover may be formedfrom a metallic material.

The posterior surface 482 of the cover 28 confronts the anterior sidesurface 82 of the base cutting block 12 when the cover 28 is securedthereto. A pair of openings 484 are defined in the posterior surface482. The openings 484 are sized and positioned to receive the shafts 84of the base cutting block 12. The cover 28 also includes a pair of grips488 defined on sides 490 of the body 480. A surgeon may use the grips488 to align the cover 28 with the base cutting block 12 and thenadvance the cover 28 over the shafts 84.

The assembly 10 may be utilized during the performance of an orthopaedicsurgical procedure similar to that shown in FIGS. 19A and 19B. As shownin FIGS. 20-23, an orthopaedic instrument construct 500 is formed fromthe intramedullary orthopaedic surgical instrument 336, theintramedullary adaptor 30, and the base cutting block 12. Theorthopaedic instrument construct 500 is attached to a distal end 502 ofa patient's femur 504, with the intramedullary orthopaedic surgicalinstrument 336 and the proximal end 314 of the intramedullary adaptor 30positioned in the medullary canal 506 of the patient's femur 504. A gapassessment may then be performed and femoral rotation set.

As shown in FIGS. 24-32, various modular cutting block 14 may beseparately secured to the base cutting block 12 (with and without theintramedullary orthopaedic surgical instrument 336 and theintramedullary adaptor 30 secured thereto). Each cutting block 14 may beused to resect portions of the distal end 502 of the patient's femur504. A guide block 362 may be attached to the base cutting block 12 toguide, for example, a surgical drill used to ream the medullary canal506.

Referring now to FIGS. 19A and 19B, an illustrative orthopaedic surgicalprocedure 600 utilizing the assembly 10 is shown. In procedure block602, the medullary canal 506 of the patient's femur 504 is initiallyprepared. To do so, an orthopaedic surgeon may drill and/or ream themedullary canal 506 to receive the intramedullary orthopaedic surgicalinstrument 336. Multiple drills or reamers may be used to increase thesize of opening 510 of the medullary canal 506 of the patient's femur504.

After preparing the medullary canal 506 of the patient's femur 504, thesurgeon may assemble the instrument construct 500 and insert theintramedullary orthopaedic surgical instrument 336 into the medullarycanal 506 in procedure block 604. To do so, the surgeon may select theintramedullary orthopaedic surgical instrument 336 from a plurality ofintramedullary orthopaedic surgical instrument 336. For example, thesurgeon may select a stem trial 328 and a stem stabilizer 320, 350 froma plurality of stem trials 328 and a plurality of stem stabilizers 320,350. The stem trials 328 may vary in length, diameter, or other aspect,and the surgeon selects the stem trial 328 based on the patient'sanatomy and the type of prosthetic stem component to be included in thefemoral prosthesis. Similarly, the stem stabilizer may be selected basedon the patient's anatomy and whether additional stability may be neededin the medullary canal 506. When the surgeon has selected an appropriatestem trial 328 and stem stabilizer 320, 350, the surgeon may thread thestem trial 328 onto the proximal end 326 of the stem stabilizer 350 toform the intramedullary orthopaedic surgical instrument 336 shown inFIG. 20.

It should also be appreciated that in other embodiments the stem trialsand stem stabilizers may be formed as single, monolithic units ofdifferent sizes and configurations. It should also be appreciated thatin other embodiments the intramedullary orthopaedic surgical instrument336 may take the form of a femoral broach having a plurality of teethconfigured to engage the patient's femur 504 when inserted into themedullary canal 506.

After selecting the intramedullary orthopaedic surgical instrument, thesurgeon may assemble the instrument construct 500 in procedure block608. To do so, the surgeon may align the end 324 of the stem stabilizer350 with the fastener 304 of the intramedullary adaptor 30. The threadedshaft 312 of the fastener 304 may be advanced into engagement with thethreaded inner wall 334 of the stem stabilizer 350. A surgeon may use adriver or other surgical tool to rotate the fastener 304 to thread theshaft 312 into the stem stabilizer 350, thereby securing theintramedullary adaptor 30 to the intramedullary orthopaedic surgicalinstrument 336. When the adaptor 30 is secured to the instrument 336,the alignment lugs 302 of the adaptor 30 are positioned arcuate slots340 of the stem stabilizer 350.

The intramedullary adaptor 30 may be then attached to the base cuttingblock 12. To do so, the mounting bracket 280 of the adaptor 30 ispositioned in the receiving slot 52 of the base cutting block 12. Asurgeon may use a driver or other surgical tool to rotate the lockingtabs 100, 102 about respective axes 112, 124 as indicated by arrows 512in FIG. 20. As the locking tabs 100, 102 rotate, the ears 114, 126 areadvanced into the channels 292, 294 defined in the mounting bracket 280,thereby securing the adaptor 30 to the block 12 and forming theinstrument construct 500 shown in FIG. 20. The surgeon may choose toattach the adaptor 30 to the base cutting block 12 before attaching theintramedullary orthopaedic surgical instrument 336 to the adaptor 30.

After the instrument construct 500 is assembled, the surgeon may insertthe intramedullary orthopaedic surgical instrument 336 into themedullary canal 506 in procedure block 610. To do so, the surgeon alignsthe end 514 of the intramedullary orthopaedic surgical instrument 336with the opening 510 of the medullary canal 506 as shown in FIG. 20. Thesurgeon may advance the instrument construct 500 such that theintramedullary orthopaedic surgical instrument 336 advances through theopening 510 and into the medullary canal 506. The fins 354, 356 of thestem stabilizer 350 are moved into engagement with the femur 504. Amallet or other surgical tool may be used to fully insert theintramedullary orthopaedic surgical instrument 336 in the medullarycanal 506 and seat the base cutting block 12 on the distal end 502 ofthe patient's femur 504. It should also be appreciated that in otherembodiments the intramedullary orthopaedic surgical instrument 336 maybe positioned in the medullary canal 506 prior to attachment to theadaptor 30.

After the intramedullary orthopaedic surgical instrument 336 ispositioned in the medullary canal 506 and the base cutting block 12 onthe distal end 502 of the patient's femur 504, the surgeon may adjustthe base cutting block 12 on the distal end 502 in procedure block 612.To do so, the surgeon may insert a driver or other surgical tool intothe socket 318 defined in the fastener 304 of the intramedullary adaptor30 to loosen the connection between the adaptor 30 and theintramedullary orthopaedic surgical instrument 336. In that way, theadaptor 30 and the base cutting block 12 are permitted to rotaterelative to the intramedullary orthopaedic surgical instrument 336. Thesurgeon also attached the cover 28 to the base cutting block 12 to coverthe exposed shafts 84.

To adjust the base cutting block 12, the surgeon performs a gapassessment in procedure block 614 and sets the femoral rotation of thebase cutting block 12 in procedure block 616. It should be appreciatedthat blocks 614, 616 may be performed in any order.

In procedure block 614, the surgeon assesses the flexion and extensiongaps through the range of motion. To do so, the surgeon selects a gapassessment tool 434. The surgeon may use only the handle 436 and one ofthe spacer ends 440, 442 having a desired thickness. Alternatively, thesurgeon may select a shim block 438. As shown in FIG. 21, the surgeonmay attach the shim block 438 to one of the spacer ends 440, 442 of thehandle 436 to assemble the gap assessment tool 434.

As shown in FIG. 21, a gap 516 is defined between the base cutting block12 and a tibial trial component 518 attached to a patient's tibia 520.With the patient's knee in flexion as shown in FIG. 21, the surgeon mayinsert the gap assessment tool 434 into the gap 516. The surgeon maymove the knee between flexion (FIG. 21) and extension (FIG. 22) toevaluate the gap 516 and the stability of the construct throughout therange of motion. The surgeon may substitute one shim block 438 for ashim block of different thickness to achieve the desired gap geometry.It should be appreciated that in other embodiments the gap assessmentmay be performed with another type of tensioning device, such as, forexample, a laminar spreader.

In procedure block 616, the surgeon sets the femoral rotation of thebase cutting block 12. To do so, the surgeon may balance the basecutting block 12 parallel to the tibial trial component 518 at 90degrees of flexion as shown in FIG. 23. The surgeon may grasp the sidewalls 132, 144 of the base cutting block 12 to rotate the base cuttingblock 12 in the direction indicated by arrow 522 until the gap 516defined between the base cutting block 12 and the tibial trial component518 is rectangular. As the base cutting block 12 is rotated, thealignment lugs 302 of the adaptor 30 are advanced along the slots 340 ofthe stem stabilizer 350. Engagement between the alignment lugs 302 andthe planar inner walls 342, 344 of the stem stabilizer 350 prevents thesurgeon from rotating the base cutting block 12 beyond a predeterminedangle. When the base cutting block 12 is balanced, the surgeon may adriver or other surgical tool to rotate the fastener 304 to secure theintramedullary adaptor 30 to the intramedullary orthopaedic surgicalinstrument 336, thereby preventing relative movement between the adaptor30 and the base cutting block 12 and the instrument 336.

Alternatively, the surgeon may set the femoral rotation by inserting twoSteinman pins (not shown) into the channels 138 defined in the side wall132, 144 of the base cutting block 12. With the Steinman pins extendingoutwardly from the block 12, the surgeon may orient the block 12referencing the medial and lateral epicondyles. When the base cuttingblock 12 is properly position, the surgeon may rotate the fastener 304to secure the intramedullary adaptor 30 to the intramedullaryorthopaedic surgical instrument 336.

Returning to FIG. 19A, the procedure 600 may proceed to procedure block618 in which the surgeon determines if the instrument construct 500requires additional stability. If the surgeon decides additionalstability is needed, the procedure 600 advances to procedure block 620in which a fixation pin 58 is inserted into a fastener guide 54 of thebase cutting block 12, as shown in FIG. 24. One or more fixation pinsmay be used to further secure the base cutting block 12 to the distalend 502 of the patient's femur 504. The procedure 600 may then proceedto procedure block 622.

If the surgeon determines in procedure block 618 that the instrumentconstruct 500 is sufficiently stable on the distal end 502 of thepatient's femur 504, the procedure 600 proceeds to procedure block 622in which the surgeon determines whether the femoral prosthesis requiresa prosthetic augment component. The surgeon may make that determinationbased on the gap assessment performed in procedure block 614. If thesurgeon determines that an augment component is unnecessary, theprocedure advances to procedure block 624. If an augment component isrequired, the procedure advances to procedure block 626.

In procedure block 626, the surgeon attaches the distal cutting block 20to the base cutting block 12. To do so, the cover 28 is detached fromthe base cutting block 12, and the distal cutting block 20 aligned withthe base cutting block 12. A surgeon may grasp the handles 182 of thelever arms 166 of the distal cutting block and push in the directionindicated by arrow 200 in FIG. 24. When the bias exerted by the springs190 is overcome, the lever arm 166 is pivoted about the axis 176 fromthe engaged position to the disengaged position.

The shafts 84 of the base cutting block 12 may then be aligned with thepassageways 180 defined in the distal cutting block 20. The distalcutting block 20 may then be advanced over the shafts 84 such thatdistal cutting block 20 confronts the anterior side surface 82 of thebase cutting block 12. The surgeon may then release the handles 182,thereby permitting the lever arms 166 to pivot back to the engagedposition. In the engaged position, the catch 94 is received in therecess 92 of the mounting brackets 24 of the base cutting block 12 andengages a posterior surface 90 of the mounting bracket 24 to secure thedistal cutting block 20 to the base cutting block 12.

After the distal cutting block 20 is secured to the base cutting block12, the surgeon may perform the distal resection in procedure block 628.To do so, the surgeon may use the cutting guides 256 defined in thedistal cutting block 20, as shown in FIG. 24. For example, the surgeonmay select the cutting guide 256 of the distal cutting block 20corresponding to a desired amount of bone to be removed. The surgeon mayperform the distal resection by inserting a bone saw blade 524 into theselected cutting guide 256 of the distal cutting block 20. The surgeonmay also utilize fastener guides 262 to attach additional fixation pinsto the patient's femur 504.

After performing the distal resection, the procedure 600 advances toprocedure block 630 in which a distal spacer block 390 is attached tothe base cutting block 12. To do so, the surgeon selects the distalspacer block 390 corresponding to the amount of bone removed during theresection. The surgeon may then align the pin 396 of the distal spacerblock 390 with the channel 138 defined in the side wall 132. As shown inFIG. 25, the surgeon may then advance the pin 396 into the channel 138such that the distal spacer block 390 is positioned between the basecutting block 12 and the distal end 502 of the patient's femur 504.

Returning to FIGS. 19A and 19B, when the surgeon determines in procedureblock 622 that an augment component is unnecessary, the procedureadvances to procedure block 624. In procedure block 624, the anteriorcutting block 16 is attached to the base cutting block 12. If a distalresection has been performed, the surgeon first removes the distalcutting block 20 from the base cutting block 12 by operating the leverarm 166 to remove the catches 94 from engagement with the shafts 84 ofthe base cutting block 12. The surgeon may then attach the anteriorcutting block 16 by operating the retention mechanism in a mannersimilar to that described above. When the anterior cutting block 16 issecured to the base cutting block 12, the procedure 600 advances toprocedure block 632.

In procedure block 632, the surgeon may use the cutting guide 156defined in the anterior cutting block 16. As shown in FIG. 26, thesurgeon may perform the anterior resection by inserting the bone sawblade 524 into the cutting guide 156 of the anterior cutting block 16.The anterior resection removes an anterior portion of the patient'sfemur 504 to create a substantially planar anterior surface.

After performing the anterior resection, the surgeon may perform theposterior resection in procedure block 634. To do so, the surgeon mayuse the posterior cutting guides 68 defined in the base cutting block12, as shown in FIG. 27. For example, the surgeon may select one or morecutting guides 68 of the base cutting block 12 corresponding to adesired amount of bone to be removed. The surgeon may perform theposterior resection by inserting the bone saw blade 524 into theselected cutting guide 68 and removing posterior portions of thepatient's femoral condyles to create a substantially planar surface. Thesurgeon may also use one or more of the posterior cutting guides 68 toperform a posterior augment resection.

After performing the posterior resection, the procedure 600 advances toprocedure block 636 in which the surgeon performs a posterior chamferresection. In procedure block 636, the surgeon may use the posteriorchamfer cutting guide 70 defined in the base cutting block 12. Thesurgeon may perform the posterior chamfer resection by inserting thebone saw blade 524 into the cutting guide 70 of the base cutting block12. The posterior chamfer resection removes a posterior chamfer portionof the patient's femur 504 to create a substantially planar anteriorsurface.

Returning now to FIG. 19B, the procedure 600 advances to procedure block638 in which the surgeon determines if the instrument construct requires500 additional stability. If the surgeon decides additional stability isneeded, the procedure 600 advances to procedure block 640 in which aposterior shim 420 is inserted into one or more the cutting guides 66defined in the base cutting block 12. To do so, the surgeon may use thegrip 424 inserts the body 422 of a posterior shim 420 into a cuttingguide 68, as shown in FIG. 28. When the shim 420 is inserted into thecutting guide 68, the spring 432 engages the base cutting block 12 toretain the posterior shim 420 in the cutting guide 66. The procedure 600may then proceed to procedure block 642.

In block 642, the surgeon attaches the notch cutting block 18 to thebase cutting block 12 after removing the anterior cutting block 16therefrom. To do so, the surgeon may then attach the notch cutting block18 by operating the retention mechanism 22 in a manner similar to thatdescribed above. When the notch cutting block 18 is secured to the basecutting block 12, the procedure 600 advances to procedure block 644.

In procedure block 644, the surgeon performs an anterior chamferresection. To do so, the surgeon may use the anterior chamfer cuttingguide 222 defined in the notch cutting block 18. The surgeon may performthe anterior chamfer resection by inserting the bone saw blade 524 intothe cutting guide 222 as shown in FIG. 28. The anterior chamferresection removes an anterior chamfer portion of the patient's femur 504to create a substantially planar anterior surface. As described above,the anterior chamfer cutting guide may be defined in the base cuttingblock 12 in other embodiments, and in such embodiments the surgeon mayuse that cutting guide to perform the anterior chamfer resection.

After performing the anterior chamfer resection, the procedure 600proceeds to procedure block 646 in which the surgeon determines whethera notch cut is required. The surgeon may make that determination basedon whether the femoral prosthetic component includes a femoral box. Ifthe surgeon determines that a notch cut is unnecessary, the procedureadvances to procedure block 648. If the notch cut is required, theprocedure advances to procedure block 650.

In procedure block 650, the surgeon utilizes the notch cutting guide 206of the block 18 to remove portions of the patient's femur 504, as shownin FIGS. 29 and 30. To do so, the surgeon may advance the bone saw bladeinto the cutting guide 206. The surgeon may engage the planar surfaces216 with the bone saw blade 524 while removing portions of the patient'sfemur 504.

The surgeon may remove the intramedullary adaptor 30 and theintramedullary orthopaedic surgical instrument 336 before completing thenotch cut. To do so, the surgeon may use a driver or other surgical toolto rotate the locking tabs 100, 102 about respective axes 112, 124 asindicated by arrows 530 in FIG. 29. As the locking tabs 100, 102 arerotated, the ears 114, 126 are advanced out of the channels 292, 294defined in the mounting bracket 280 such that the adaptor 30 isdecoupled from the block 12. The adaptor 30 and the intramedullaryorthopaedic surgical instrument 336 may then be removed from thepatient's femur 504.

As shown in FIG. 30, the surgeon may advance the bone saw blade 524 intothe cutting guide 206. The surgeon may engage the planar surface 212with the bone saw blade 524 to remove a portion of the patient's femur504, thereby completing the notch cut. After completing the notch cut,the procedure 600 may advance to procedure block 648.

Returning to FIG. 19B, if the surgeon determined in procedure block 646that a notch cut is unnecessary, the procedure also advance to procedureblock 648. In block 648, one of the guide blocks 362, 386 is selectedand attached to the base cutting block 12. To do so, the surgeon mayselect the guide block 362 and position the mounting bracket 364 in thereceiving slot 52 of the base cutting block 12, as shown in FIG. 31. Asurgeon may use a driver or other surgical tool to rotate the lockingtabs 100, 102 about respective axes 112, 124 as indicated. As thelocking tabs 100, 102 are rotated, the ears 114, 126 are advanced intothe channels 372 defined in the mounting bracket 364, thereby securingthe guide block 362 to the block 12.

The procedure 600 may then advance to procedure block 652 in which thesurgeon reams the patient's femur 504 to a desired depth. To do so, areamer 532 may be inserted into the passageway 380 defined in the guideblock 362. The reamer 532 may then be engaged with the patient's femurand operated to remove the desired amount of bone.

As shown in FIG. 32, the surgeon may select the guide block 386 andattach the block 386 to the base cutting block 12. A reamer 534 may beinserted into the passageway 388 defined in the guide block 386. Thereamer 534 may then be engaged with the patient's femur and advancedinto the medullary canal 506 until a line 536 corresponding to a desireddepth is aligned with the upper surface 538 of the guide block 386.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as exemplary and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the method, apparatus, and system describedherein. It will be noted that alternative embodiments of the method,apparatus, and system of the present disclosure may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the method, apparatus, andsystem that incorporate one or more of the features of the presentinvention and fall within the spirit and scope of the present disclosureas defined by the appended claims.

The invention claimed is:
 1. A method for performing an orthopaedicsurgical procedure on a femur, the method comprising: positioning adistal end of an intramedullary adaptor in a slot defined in a basecutting block, securing the distal end of the intramedullary adaptor tothe base cutting block, attaching a proximal end of the intramedullaryadaptor to an intramedullary orthopaedic surgical instrument aftersecuring the intramedullary adaptor to the base cutting block, andpositioning the base cutting block on a distal end of the femur, whereinsecuring the distal end of the intramedullary adaptor to the basecutting block includes advancing a locking tab of the base cutting blockinto the slot defined in the base cutting block and into a channeldefined in distal end of the intramedullary adaptor.
 2. The method ofclaim 1, further comprising advancing the intramedullary orthopaedicsurgical instrument through an opening defined in the distal end of thefemur into a medullary canal of the femur after attaching theintramedullary adaptor to the intramedullary surgical instrument.
 3. Themethod of claim 2, further comprising securing a stem trial to a stemstabilizer to form the intramedullary orthopaedic surgical instrument.4. The method of claim 3, wherein the stem stabilizer has a plurality offins extending outwardly therefrom, and advancing the intramedullaryorthopaedic surgical instrument into the medullary canal includesengaging the plurality of fins with bone surrounding the medullarycanal.
 5. The method of claim 1, wherein attaching the proximal end ofthe intramedullary adaptor to the intramedullary orthopaedic surgicalinstrument includes threading a shaft of the intramedullary adaptor intoan internally-threaded distal end of the intramedullary surgicalinstrument.
 6. The method of claim 1, further comprising: attaching amodular cutting block to an anterior surface of the base cutting block,and resecting the femur using a cutting guide defined in the modularcutting block.
 7. A method for performing an orthopaedic surgicalprocedure on a femur, the method comprising: securing a stem trial to astem stabilizer to form an intramedullary orthopaedic surgicalinstrument, securing a proximal end of an intramedullary adaptor to adistal end of the stem stabilizer by (i) aligning a shaft of theintramedullary adaptor with an aperture defined in the distal end of thestem stabilizer, and (ii) rotating the shaft of the intramedullaryadaptor in a first direction to advance the shaft into the aperture andprevent an adaptor body of the intramedullary adaptor from movingrelative to the stem stabilizer, positioning a mounting bracket of theintramedullary adaptor in a slot defined in a base cutting block,placing a locking tab of the base cutting block in a channel defined inthe mounting bracket of the intramedullary adaptor, advancing theintramedullary orthopaedic surgical instrument and the proximal end ofthe intramedullary adaptor through an opening defined in a distal end ofthe femur, and positioning the base cutting block on the distal end ofthe femur.
 8. The method of claim 7, further comprising assessing a gapdefined between the base cutting block and a tibial component.
 9. Amethod for performing an orthopaedic surgical procedure on a femur, themethod comprising: attaching a proximal end of an intramedullary adaptorto an intramedullary orthopaedic surgical instrument, advancing a distalend of the intramedullary adaptor into a central opening of a basecutting block that extends through the base cutting block, securing thedistal end of the intramedullary adaptor to the base cutting blockwithin the central opening, inserting the intramedullary orthopaedicsurgical instrument into a medullary canal using the base cutting block,and positioning the base cutting block on a distal end of the femur. 10.The method of claim 9, further comprising: attaching a modular cuttingblock to an anterior surface of the base cutting block, and resectingthe femur using a cutting guide defined in the modular cutting block.